Copperhead snakes are some of the most commonly encountered venomous snakes in North America. They are responsible for more bites in the U.S. than any other snake species, but bites are rarely fatal.
Copperhead snakes (Agkistrodon contortix) range from the Florida panhandle, north to Massachusetts and west to Nebraska. There are five subspecies of copperheads, which are named after their reddish-brown heads. While North American copperheads make up their own species, several types of snakes are colloquially referred to as copperheads, including cottonmouth snakes (Agkistrodon piscivorus), radiated rat snakes (Coelognathus radiata), lowland copperheads (Austrelaps superbus) and sharp-nosed pit vipers (Deinagkistrodon acutus).
North American copperheads are pit vipers — snakes that have heat-sensitive pit organs between the eye and the nostril on each side of their head. These pits detect minute differences in temperature in the environment, including sources of warmth that often turn out to be prey for the snakes. Pit vipers are mostly nocturnal, and copperhead "behavior is very much like that of most other pit vipers," said Jeffrey Beane, a collections manager in herpetology (the study of reptiles and amphibians) at the North Carolina Museum of Natural Sciences.
What do copperhead snakes look like?
Copperhead snakes are medium-size snakes, averaging between 2 and 3 feet (0.6 to 0.9 meters) in length. According to the Smithsonian National Zoological Park, female copperheads are longer than males; however, males possess proportionally longer tails.
According to Beane, copperhead snake bodies are distinctly patterned. Their "dorsal pattern is a series of dark, chestnut-brown or reddish-brown crossbands, each shaped like an hourglass, dumbbell or saddlebag … on a background of lighter brown, tan, salmon or pinkish," Beane said. He further described the saddlebags as "wide on sides of body, narrow in center of back — the crossbands typically have darker margins and lighter lateral centers." Meanwhile, "some crossbands may be broken, and sometimes small dark spots may be in the spaces between the crossbands."
Several other nonvenomous species of snakes have similar coloring, and so are frequently confused for copperheads. However, copperheads are the only kind of snakes with hourglass-shaped markings.
In contrast to its patterned body, the snake's coppery-brown head lacks such adornments, "except for a pair of tiny dark dots usually present on top of the head," said Beane. He described copperheads' bellies as "whitish, yellowish or a light brownish, stippled or mottled, with brown, gray or blackish, often large, paired dark spots or smudges along sides of [its] belly."
Copperheads have muscular, thick bodies and keeled (ridged) scales. Their heads are "somewhat triangular/arrow-shaped and distinct from the neck," with a "somewhat distinct ridge separating [the] top of head from side snout between eye and nostril," said Beane. Their pupils are vertical, like cats' eyes, and their irises are usually orange, tan or reddish-brown.
Young copperheads are more grayish in color than adults and possess "bright yellow or greenish yellow tail tips." According to Beane, "this color fades in about a year."
Copperhead snake bite
Copperheads bite more people in most years than any other U.S. species of snake, according to the North Carolina State University Cooperative Extension Service. Fortunately, copperhead venom is not very potent.
Unlike most venomous snakes, copperheads give no warning signs and strike almost immediately if they feel threatened. Copperheads have hemotoxic venom, said Beane, which means that a copperhead bite "often results in temporary tissue damage in the immediate area of bite." Their bite may be painful but is "very rarely (almost never) fatal to humans." Children, the elderly and people with compromised immune systems may have strong reactions to the venom, however, and anyone who is bitten by a copperhead should seek medical attention.
Despite this, Beane thinks you should still let a Copperhead snake live in your back yard. He told North Carolina's Blue Ridge Public Radio that, "if you encounter them and they're coiled up somewhere where they want to be, they'll remain completely still and hope that you don't see them or bother them... If you do disturb them, the first thing they'll probably do is try to get away. If you move them... they're going to try to get back to something that's familiar."
Bean also talked about the benefits of having a Copperhead near your house: "They eat a lot of species that we don't like, like mice and rats, that can cause diseases and problems. And [by] eating a lot of rodents, snakes are swallowing a lot of ticks. And ticks cause things like Rocky Mountain spotted fever and Lyme disease. One study showed that snakes are significant tick destroyers in Eastern forest sites."
Where do copperheads live?
Copperheads reside "from southern New England to West Texas and northern Mexico," said Beane, advising those interested to check out range maps in a number of field guides.
There are five subspecies of copperhead distributed according to geographic range: the northern, northwestern, southern and two southwestern subspecies. According to the Smithsonian National Zoological Park, the northern copperhead has by far the largest range, from Alabama to Massachusetts and Illinois.
According to Beane, copperheads are happy in "an extremely wide range of habitats," though usually "at least some semblance of woods or forest habitat is present." They are "particularly fond of ecotones," which are transition areas between two ecological communities. They like rocky, wooded areas, mountains, thickets near streams, desert oases, canyons and other natural environments, according to Penn State; Beane added that they like "almost any habitat with both sunlight and cover."
According to the Savannah River Ecology Laboratory, copperheads are "quite tolerant of habitat alteration." This means that they can survive well in suburban areas. Copperheads can sometimes be found in wood and sawdust piles, abandoned farm buildings, junkyards and old construction areas. They "often seek shelter under surface cover such as boards, sheet metal, logs or large flat rocks," said Beane.
Copperhead snake behavior
Copperheads are semi-social snakes. While they usually hunt alone, they usually hibernate in communal dens and often return to the same den every year. Beane said that populations in the "montane" (a forest area below the timberline with large, coniferous trees) often spend the winter hibernating "with timber rattlesnakes, rat snakes or other species." However, "Piedmont and Coastal Plain snakes are more likely to hibernate individually," Beane said. They also can be seen near one another while basking in the sun, drinking, eating and courting, according to the Smithsonian Zoo.
According to the Ohio Public Library Information Network, copperheads are usually out and about during the day in the spring and fall, but during the summer they become nocturnal. They especially like being out on humid, warm nights after rain. While they usually stay on the ground, copperheads will sometimes climb into low bushes or trees in search of prey or to bask in the sun. Sometimes, they even voluntarily go swimming.
According to Animal Diversity Web (ADW), a database maintained by the University of Michigan Museum of Zoology, scientists have hypothesized that copperheads migrate late in the spring to their summer feeding area, then return home in early fall.
What do copperheads eat?
Beane described copperheads as being "mobile ambush predators." The snakes mostly attack unsuspecting prey that pass their hiding place, but they are also known to hunt using their heat-sensing pit organs.
When attacking large prey, copperheads bite and then release their target. They let the venom kill it before tracking the carcass down. If the prey item is small enough, copperheads will hold it in their mouth until it dies. Copperheads eat their food whole, opening their hinged jaws wide to swallow prey down in one go. According to Penn State, adult copperheads may only eat 10 or 12 meals per year, depending on the size of prey.
Copperhead snake reproduction
Copperhead mating season lasts from February to May and from late August to October, and it can be a dramatic affair. "Males may engage in ritual combat (body-shoving contests) when two or more meet in the presence of a receptive female," said Beane. According to Penn State, the snakes that lose rarely challenge again. A female may also fight prospective partners, and will always reject males who back down from a fight with her.
Copperheads are ovoviviparous, which means that eggs incubate inside the mother's body. Babies are born live. After mating in the spring, females will give birth to "from two to 18 live young in late summer or fall," said Beane. According to The Maryland Zoo, after mating in the fall, the female will store sperm and defer fertilization for months, until she has finished hibernating. Baby copperheads are born with fangs and venom as potent as an adult's, according to the Smithsonian Zoo.
Young copperheads are 8 to 10 inches (20 to 25 cm) long and are born with both fangs and venom, according to Penn State. They eat mostly insects, especially caterpillars.
Beane pointed out that young copperheads may exhibit different hunting patterns than adults. "Young snakes may sit otherwise motionless, flicking their yellow tail tips," he said. "This is known as 'caudal luring'; the tail resembles a small caterpillar or other insect and may attract a lizard or frog [to come] within striking range."
Classification and taxonomy
According to the Integrated Taxonomic Information System (ITIS), the taxonomy of copperheads is:
Kingdom: Animalia
Subkingdom: Bilateria
Infrakingdom: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Superclass: Tetrapoda
Class: Reptilia
Order: Squamata
Suborder: Serpentes
Infraorder: Alethinophidia
Family: Viperidae
Subfamily: Crotalinae
Genus & species: Agkistrodon contortrix
Subspecies:
- Agkistrodon contortrix contortrix (Southern copperhead),
- Agkistrodon contortrix laticinctus (broad-banded copperhead),
- Agkistrodon contortrix mokasen (Northern copperhead),
- Agkistrodon contortrix phaeogaster (Osage copperhead)
- Agkistrodon contortrix pictigaster (trans-Pecos copperhead)
Medicinal use for copperhead snake venom
A 2018 review in the journal Toxins found that snake venom in general is "recognized as a potential source of biologically active compounds" that can be used in cancer treatments. In a 1999 study, scientists discovered that a protein in copperhead venom called contortrostatin may limit the growth of cancerous tumors. The team injected contortrostatin from southern copperheads (Agkistrodon contortix contortix) into the mammary glands of mice where they had introduced human breast cancer two weeks earlier.
Contortrostatin inhibited the growth of breast cancer tumors and also slowed the growth of blood vessels that were supplying the tumors with nutrients. The protein also stopped the spread of tumors to the lungs, where breast cancer often spreads to. A 2013 study bolstered these findings through studying the effect of contortrostatin on human breast cancer cell cultures. The protein majorly disrupted the cells' structure, as well as their ability to move and change shape, eventually leading to cancer cell death.
More facts about copperheads
- The length of a copperhead's fangs is related to the length of the snake — the longer the snake, the longer the fangs.
- When touched, copperhead snakes sometimes emit a musk that smells like cucumbers.
- The penny is sometimes called a copperhead.
- Northern Democrats who opposed the U.S. Civil War were called Copperheads, according to the Journal of the Abraham Lincoln Association.
Additional resources
How dangerous are copperheads? The Cooperative Extension Service at North Carolina State University puts it simply: "Avoid Copperhead snakes!" Learn more about copperheads on the Animal Diversity Web. Check out the Smithsonian Zoo's detailed fact sheet about copperheads.
Originally published on Live Science Dec. 16, 2021 and updated Aug. 16, 2023.
